Clustered Palette Compression

ABSTRACT

Color values may be compressed using a palette based encoder. Clusters of color values may be identified and encoded color values within the cluster with respect to a color value having a predefined characteristic. Clusters that have pixels or samples with constant color value may also be encoded.

BACKGROUND

Traffic to and from memory is a large power consumer in a computersystem. Therefore, it is of utmost importance to develop techniques thatreduce the memory traffic.

One way to reduce power consumption from memory traffic is to use acache hierarchy and another is to employ different types of compressionof the data that is being transported.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments are described with respect to the following figures:

FIG. 1 is a depiction of palette compression according to oneembodiment;

FIG. 2 is a depiction of palette compression with clustering accordingto one embodiment;

FIG. 3 is a flow chart for one embodiment;

FIG. 4 is a depiction of a clustering algorithm according to oneembodiment;

FIG. 5 is a graph of red and green channels in one hypothetical example;

FIG. 6 is a block diagram of a processing system according to oneembodiment;

FIG. 7 is a block diagram of a processor according to one embodiment;

FIG. 8 is a block diagram of a graphics processor according to oneembodiment;

FIG. 9 is a block diagram of a graphics processing engine according toone embodiment;

FIG. 10 is a block diagram of another embodiment of a graphicsprocessor;

FIG. 11 is a depiction thread execution logic according to oneembodiment;

FIG. 12 is a block diagram of a graphics processor instruction formataccording to some embodiments;

FIG. 13 is a block diagram of another embodiment of a graphicsprocessor;

FIG. 14A is a block diagram of a graphics processor command formataccording to some embodiments;

FIG. 14B is a block diagram illustrating a graphics processor commandsequence according to some embodiments;

FIG. 15 is a depiction of an exemplary graphics software architectureaccording to some embodiments;

FIG. 16 is a block diagram illustrating an IP core development systemaccording to some embodiments; and

FIG. 17 is a block diagram showing an exemplary system on chipintegrated circuit according to some embodiments.

DETAILED DESCRIPTION

For certain areas of a rendered image, the best choice ofcompression-decompression (codec) is to use a palette-based codec.Palette-based compression may be based on clustering, which makes theactual palette much smaller to store, in turn improving compressionsuccess rates.

The palette in itself is a large portion of the entire compressedrepresentation in a palette-based codec. The palette may be compressedusing both a clustered approach and by skip encoding color channels thatare constant.

The task at hand is to: (i) collect all individual colors in the tileand store these in a palette, and (ii) assign each sample/pixel value anindex to this palette. The data collected, depicted in FIG. 1, involvesconverting each of the colors (in this case these are only threecolors), identifying each by a code or index (0, 1 or 2 in this example)and creating a palette which shows which colors (3) of the palette ofavailable colors (in this case 4) is actually being used.

At the end of this process, the total number of bits needed to store thepalette along with the palette indices are counted. Then a checkdetermines whether this number of bits fits in the bit budget of thecompressed unit. This check may involve determining whether the proposedcompression results in fewer number of cache lines than in raw format.If so, compression is achieved.

The palette itself takes fewer bytes to store than the fullrepresentation, and so, this will make the compression success ratehigher in some cases. This, in turn, will reduce memory traffic and willincrease energy efficiency, in some embodiments.

Given a palette-based codec, consisting of N colors, a palette is storedand then each pixel/sample needs k=ceil(log₂ N) index bits to “point”into the color palette. The colors in the palette are compressed, sothey take up less space.

For example, for an 8×4 pixel tile, where each color takes 32 bits(RGBA), the uncompressed tile uses 32*4=128 bytes. Assume compression to64 bytes, i.e., 512 bits is required. Each pixel needs k bits for theindex, i.e., 32*k bits in total are needed. Each color in the paletteuses 32 bits (same as original data in the tile), and there are Npalette colors. In total, this sums to 32*k+32*N which is less than orequal to 512.

In this case, this means that k+N is less than or equal to 16, andhence, it makes sense to use k=4 bits, which in theory makes it possibleto use at most 2⁴ or 16 different colors in the palette. Then, there are512−4*32 or 384 bits left for the color palette, and this means that Nis 384/32 or 12 colors in the palette.

However, one could compress more tiles if one were able to store 16colors in the palette, and by using compression of the colors in thepalette, this goal can be achieved. Alternatively, one can use k=5 bits,which gives (512−32*5)/32 or 11 colors in the palette. Since there are 5bits per index, one can potentially use a palette with up to 32 colors.However, this can only be done if the palette is compressed.

As a first simple technique, one bit per color channel is used toindicate whether color is constant in one of the color channels. If abit is 1, as an example, all pixels in the tile have the same value forthat channel. For example, all red values may be 23. In this case, theconstant value, i.e., 23 is also stored.

As an example, using the RGBA color space, the alpha (A) component isoften 0 all over the tile, or 255 all over the tile. If one colorchannel is skipped, 8 bits are stored for the constant channel, sincethese are 32 bits for RGBA or 8 bits per channel times 4 values. A skipbit is also stored for each of the four channels to indicate whether thechannel is skipped. So, in total, an extra 12 bits are stored in theexample of having one constant color, and so each color in the paletteis now only 24 (3*8) bits.

In the case with k=5 bits, N equals (512−12−32*5)/24=14.167 colors, orrounding down, 14 colors in the palette, compared to 11 colors before.

This compression technique can be called the skip bit technique. Morethan one channel may be constant. If two channels are constant, then the4 skip bits and then 8+8 bits are stored for the constant channels, andso on.

In addition, one can store the minimum color value of all colors in thepalette, and then encode the difference between a color in the paletteand this minimum color. These differences can often be encoded done withfewer bits.

However, in many cases, the palette encoding method beats other encodingmethods. These cases often include tiles where there are distinct groupsof colors in the palette.

For example, assume a very dark gray background with a bit of noise init, and then suddenly two white pixels appear. The difference from theminimum color (which would be the darkest gray) and the white pixels ishuge, and all differences would be encoded with as many bits that areneeded for the difference between white and the darkest gray pixel. As aresult, no compression can be obtained. In this case, there were onlytwo pixels that destroyed the possibility of compression. However thesesituations often occur in user interfaces, for example, and it isadvantageous if they are very compressible.

The palette may be compressed using clustering. Clustering involvesfinding two or more minimum (lowest color value) colors and thencompressing each color in the palette relative to one of these minimumcolors. In the example above, the minimum dark gray color may be oneminimum color, and the white color is one minimum color. All dark graycolors (called cluster 1) are encoded relative the minimum dark graycolor, and the two white colors (called cluster 2) are encoded relativeto the minimum white color.

Then skip bits can be used for each cluster. This can actually reducedata more as well.

An example of clustering is shown in FIG. 2 for one embodiment usingresidual bits per sample/pixel, in addition to the color (now cluster)indices. In FIG. 2 there are only two redish colors (cross-hatched anddouble cross-hatched) and one blue color (no hatching) (using indices 0(for the blue color) and 1 (for the two redish colors)). The residualbits encode the difference of one of the two redish color values fromthe minimum color value. The palette in this example only has twocolors, with one of the variant red colors indicated via residual bits.

There are several ways to find clusters. Assume that one wants to findonly two clusters. In this case, two colors that can act as “means” arefound. The better these guesses are for the means, the faster the methodwill converge.

The means can be found, in one embodiment, by finding a minimal boundingbox around the color in the space of the remaining color channels, e.g.,RGB or RGBA, or RGA (if B is constant and, thus, skipped). Next, assumethat the minimal bounding box is split in the middle in each colordimension, and this results in a number of sub-boxes. Next, the colorsthat are closest to each corner of this minimal bounding box are found.Two of these “corner colors” are picked, each having the most colors inits sub-box. These colors are the two means to initialize a k-meansclustering algorithm.

Next, apply one or more steps of k-means clustering. The first step issimply to associate each color with the means that it is closest to (inRGB space, for example). When this has been done, each color in thepalette has been assigned to one means (which is a color from thepalette). The second step updates each means as the average of all thecolors assigned to that cluster. Then one may do steps one and two a fewmore times if needed.

Yet another variant is more iterative. The idea is to take one colorfrom the palette and build a cluster around that color as long as theadded colors are sufficiently close. If a color is encountered that istoo far away from the current cluster, then a new cluster color isallocated. Continue with the rest of the colors, and attempt to mergethem into either of the current two clusters. Then a third cluster canbe added, etc. To enable this, one bit per sample/pixel is used tosignal if residual bits are stored or not.

Thus, referring to FIG. 4, a sequence 40 may be implemented in software,firmware and/or hardware. In software and firmware embodiments, it maybe implemented by computer executed instructions stored in one or morenon-transitory computer readable media, such as magnetic, optical, orsemiconductor storage.

The sequence begins by looping over all samples or pixels in a tile, asindicated in block 42. Then, the difference between a given color andcolors already in the palette is checked, as indicated in block 44. Ifthe difference is small because it is less than a threshold, asdetermined in diamond 46, then store residual bits and mark the sample,as indicated in block 48. The residual bits are indicated at 50.

On the other hand, if the difference is not small, a check at diamond 52determines whether the color is already in the palette. If not, thecolor is stored in the palette, as indicated in block 54. Then thepalette is updated, as indicated at 56 and the flow iterates back toblock 44.

If the color is already in the palette, as determined in diamond 52, thepalette entry identifier (ID) is recorded, as indicated in block 48.Then the sample or pixel is provided in the palette entry list, asindicated at 60.

A check at diamond 62 determines whether there are any samples or pixelsleft. If so, the flow iterates back to block 44 and, otherwise, the flowends.

The selection between storing a new palette entry or residual bitsagainst an existing color, is arbitrary. In the general case, a gain innumber of stored bits can be achieved as long as the number of residualbits per entry plus one bit per sample, is lower than a full color inthe palette.

Assume that we have a tile with N colors, with RGB, for example. Thereis nothing that restricts this technique to any particular color space.

In FIG. 5, an example is given that only visualizes the red and greenchannels (R and G). To the left, the red (R) and green (G) axes arelabelled. There are 8 pixel colors here. Green pixels or samples areindicated by open circles and red pixels or samples are indicated bysolid circles. In the middle, the minimal box around the pixel colorsare found. The circle D is at the left-bottom corner, and so this is theminimum color of these 8 pixel colors. In the middle, split the minimalbox into four 2×2 cells (indicated in dashed lines). To the right, theminimal boxes B1 and B2 are computed for each cell, which created twogroups. The dark circles D1 and D2 show the minimal colors for these twogroups.

In one clustering algorithm, simply encode each non-empty cell with theminimum color (dark circles D1 and D2 in FIG. 4) and then add someencoding of residuals inside that box. This may be done with standardmethods.

This example is in two dimensions, but usually there are three (RGB) orfour (RGBA) dimensions. Since the coding of the minimal color of a groupis rather expensive, sometimes it makes sense to merge two groups intoone. One may also choose to transform the colors into another colorspace, such that YCoGg, in order to reduce the volume of each box,therefore reducing the number of residual bits.

In an iterative scheme, one pair of groups (boxes) that increases thetotal volume of the resulting merged groups (boxes) the least, aremerged. In RGB-space, 8 cells are obtained by splitting once perdimension. Each group only has one direct neighbor in x, y or z. Thereare several heuristics to use here including the following examples:

-   -   1) Merge the smallest box with the neighbor that gives the        smallest volume. Do this iteratively until the cost falls below        the bit threshold for successful compression.    -   2) Merge the smallest box with the neighbor that gives the        largest volume. Do this iteratively until the cost falls below        the bit threshold for successful compression.

Merging only needs to continue until the target bit threshold is reached(or less). There is also the possibility to split more than once perdimension. This creates more cells whose minimal boxes must be merged.Each cell may get more direct neighbors in this case.

After two or more clusters have been generated, the minimum color ofeach cluster is stored. In addition, as mentioned above, the 4 skip bitsmay be stored per cluster, and if a channel is constant within acluster, then that channel need not encode residuals. In this case 3size bits are stored per channel to indicate how many residual bits areneeded per channel. For example, if the maximum difference for the redchannel within a cluster is 13, then 4 bits are needed to store suchdifferences, and hence then 3 size bits will be set to 4 in this case.

Sequence 34, as shown in FIG. 3, for compression using clustering, maybe implemented in software, firmware and/or hardware. In software andfirmware embodiments it may be implemented by computer executedinstructions stored in one or more non-transitory computer readablemedia such as a magnetic, optical or semiconductor storage. The sequencemay be implemented for example by a graphics processing unit in somecases.

The sequence 34 begins by looping over a tile (block 12). A tile issimply an image portion containing samples or pixels. First any constantcolor channels are found as indicated in block 14. Then clusters arefound in block 16, coded in block 18 and added to palette 24. Anyclusters that are of constant color may also be skipped but encoded aswell. One may also use separate skip bits per cluster, which may beuseful in some cases. In block 20, the flow loops over all samples orpixels in a tile. A cluster or palette entry is selected in block 22.

The palette entry identification and residual is encoded, as indicatedin block 26. The sample or pixel residual values 30 are stored. Thesample or pixel is stored in the palette entry list 28.

A check at diamond 32 indicates whether there are more samples or pixelsleft to process and if so, the flow iterates back to loop over the tile.Otherwise, the flow ends.

With the described difference encoding in each cluster, bettercompression of the palette may be obtained, and this will make thesuccession rate for compression substantially higher, and compressionhardware for color buffers will succeed more often, and as a result, thepower usage will be reduced in some embodiments.

FIG. 6 is a block diagram of a processing system 100, according to anembodiment. In various embodiments the system 100 includes one or moreprocessors 102 and one or more graphics processors 108, and may be asingle processor desktop system, a multiprocessor workstation system, ora server system having a large number of processors 102 or processorcores 107. In on embodiment, the system 100 is a processing platformincorporated within a system-on-a-chip (SoC) integrated circuit for usein mobile, handheld, or embedded devices.

An embodiment of system 100 can include, or be incorporated within aserver-based gaming platform, a game console, including a game and mediaconsole, a mobile gaming console, a handheld game console, or an onlinegame console. In some embodiments system 100 is a mobile phone, smartphone, tablet computing device or mobile Internet device. Dataprocessing system 100 can also include, couple with, or be integratedwithin a wearable device, such as a smart watch wearable device, smarteyewear device, augmented reality device, or virtual reality device. Insome embodiments, data processing system 100 is a television or set topbox device having one or more processors 102 and a graphical interfacegenerated by one or more graphics processors 108.

In some embodiments, the one or more processors 102 each include one ormore processor cores 107 to process instructions which, when executed,perform operations for system and user software. In some embodiments,each of the one or more processor cores 107 is configured to process aspecific instruction set 109. In some embodiments, instruction set 109may facilitate Complex Instruction Set Computing (CISC), ReducedInstruction Set Computing (RISC), or computing via a Very LongInstruction Word (VLIW). Multiple processor cores 107 may each process adifferent instruction set 109, which may include instructions tofacilitate the emulation of other instruction sets. Processor core 107may also include other processing devices, such a Digital SignalProcessor (DSP).

In some embodiments, the processor 102 includes cache memory 104.Depending on the architecture, the processor 102 can have a singleinternal cache or multiple levels of internal cache. In someembodiments, the cache memory is shared among various components of theprocessor 102. In some embodiments, the processor 102 also uses anexternal cache (e.g., a Level-3 (L3) cache or Last Level Cache (LLC))(not shown), which may be shared among processor cores 107 using knowncache coherency techniques. A register file 106 is additionally includedin processor 102 which may include different types of registers forstoring different types of data (e.g., integer registers, floating pointregisters, status registers, and an instruction pointer register). Someregisters may be general-purpose registers, while other registers may bespecific to the design of the processor 102.

In some embodiments, processor 102 is coupled to a processor bus 110 totransmit communication signals such as address, data, or control signalsbetween processor 102 and other components in system 100. In oneembodiment the system 100 uses an exemplary ‘hub’ system architecture,including a memory controller hub 116 and an Input Output (I/O)controller hub 130. A memory controller hub 116 facilitatescommunication between a memory device and other components of system100, while an I/O Controller Hub (ICH) 130 provides connections to I/Odevices via a local I/O bus. In one embodiment, the logic of the memorycontroller hub 116 is integrated within the processor.

Memory device 120 can be a dynamic random access memory (DRAM) device, astatic random access memory (SRAM) device, flash memory device,phase-change memory device, or some other memory device having suitableperformance to serve as process memory. In one embodiment the memorydevice 120 can operate as system memory for the system 100, to storedata 122 and instructions 121 for use when the one or more processors102 executes an application or process. Memory controller hub 116 alsocouples with an optional external graphics processor 112, which maycommunicate with the one or more graphics processors 108 in processors102 to perform graphics and media operations.

In some embodiments, ICH 130 enables peripherals to connect to memorydevice 120 and processor 102 via a high-speed I/O bus. The I/Operipherals include, but are not limited to, an audio controller 146, afirmware interface 128, a wireless transceiver 126 (e.g., Wi-Fi,Bluetooth), a data storage device 124 (e.g., hard disk drive, flashmemory, etc.), and a legacy I/O controller 140 for coupling legacy(e.g., Personal System 2 (PS/2)) devices to the system. One or moreUniversal Serial Bus (USB) controllers 142 connect input devices, suchas keyboard and mouse 144 combinations. A network controller 134 mayalso couple to ICH 130. In some embodiments, a high-performance networkcontroller (not shown) couples to processor bus 110. It will beappreciated that the system 100 shown is exemplary and not limiting, asother types of data processing systems that are differently configuredmay also be used. For example, the I/O controller hub 130 may beintegrated within the one or more processor 102, or the memorycontroller hub 116 and I/O controller hub 130 may be integrated into adiscreet external graphics processor, such as the external graphicsprocessor 112.

FIG. 7 is a block diagram of an embodiment of a processor 200 having oneor more processor cores 202A-202N, an integrated memory controller 214,and an integrated graphics processor 208. Those elements of FIG. 7having the same reference numbers (or names) as the elements of anyother figure herein can operate or function in any manner similar tothat described elsewhere herein, but are not limited to such. Processor200 can include additional cores up to and including additional core202N represented by the dashed lined boxes. Each of processor cores202A-202N includes one or more internal cache units 204A-204N. In someembodiments each processor core also has access to one or more sharedcached units 206.

The internal cache units 204A-204N and shared cache units 206 representa cache memory hierarchy within the processor 200. The cache memoryhierarchy may include at least one level of instruction and data cachewithin each processor core and one or more levels of shared mid-levelcache, such as a Level 2 (L2), Level 3 (L3), Level 4 (L4), or otherlevels of cache, where the highest level of cache before external memoryis classified as the LLC. In some embodiments, cache coherency logicmaintains coherency between the various cache units 206 and 204A-204N.

In some embodiments, processor 200 may also include a set of one or morebus controller units 216 and a system agent core 210. The one or morebus controller units 216 manage a set of peripheral buses, such as oneor more Peripheral Component Interconnect buses (e.g., PCI, PCIExpress). System agent core 210 provides management functionality forthe various processor components. In some embodiments, system agent core210 includes one or more integrated memory controllers 214 to manageaccess to various external memory devices (not shown).

In some embodiments, one or more of the processor cores 202A-202Ninclude support for simultaneous multi-threading. In such embodiment,the system agent core 210 includes components for coordinating andoperating cores 202A-202N during multi-threaded processing. System agentcore 210 may additionally include a power control unit (PCU), whichincludes logic and components to regulate the power state of processorcores 202A-202N and graphics processor 208.

In some embodiments, processor 200 additionally includes graphicsprocessor 208 to execute graphics processing operations. In someembodiments, the graphics processor 208 couples with the set of sharedcache units 206, and the system agent core 210, including the one ormore integrated memory controllers 214. In some embodiments, a displaycontroller 211 is coupled with the graphics processor 208 to drivegraphics processor output to one or more coupled displays. In someembodiments, display controller 211 may be a separate module coupledwith the graphics processor via at least one interconnect, or may beintegrated within the graphics processor 208 or system agent core 210.

In some embodiments, a ring based interconnect unit 212 is used tocouple the internal components of the processor 200. However, analternative interconnect unit may be used, such as a point-to-pointinterconnect, a switched interconnect, or other techniques, includingtechniques well known in the art. In some embodiments, graphicsprocessor 208 couples with the ring interconnect 212 via an I/O link213.

The exemplary I/O link 213 represents at least one of multiple varietiesof I/O interconnects, including an on package I/O interconnect whichfacilitates communication between various processor components and ahigh-performance embedded memory module 218, such as an eDRAM module. Insome embodiments, each of the processor cores 202-202N and graphicsprocessor 208 use embedded memory modules 218 as a shared Last LevelCache.

In some embodiments, processor cores 202A-202N are homogenous coresexecuting the same instruction set architecture. In another embodiment,processor cores 202A-202N are heterogeneous in terms of instruction setarchitecture (ISA), where one or more of processor cores 202A-N executea first instruction set, while at least one of the other cores executesa subset of the first instruction set or a different instruction set. Inone embodiment processor cores 202A-202N are heterogeneous in terms ofmicroarchitecture, where one or more cores having a relatively higherpower consumption couple with one or more power cores having a lowerpower consumption. Additionally, processor 200 can be implemented on oneor more chips or as an SoC integrated circuit having the illustratedcomponents, in addition to other components.

FIG. 8 is a block diagram of a graphics processor 300, which may be adiscrete graphics processing unit, or may be a graphics processorintegrated with a plurality of processing cores. In some embodiments,the graphics processor communicates via a memory mapped I/O interface toregisters on the graphics processor and with commands placed into theprocessor memory. In some embodiments, graphics processor 300 includes amemory interface 314 to access memory. Memory interface 314 can be aninterface to local memory, one or more internal caches, one or moreshared external caches, and/or to system memory.

In some embodiments, graphics processor 300 also includes a displaycontroller 302 to drive display output data to a display device 320.Display controller 302 includes hardware for one or more overlay planesfor the display and composition of multiple layers of video or userinterface elements. In some embodiments, graphics processor 300 includesa video codec engine 306 to encode, decode, or transcode media to, from,or between one or more media encoding formats, including, but notlimited to Moving Picture Experts Group (MPEG) formats such as MPEG-2,Advanced Video Coding (AVC) formats such as H.264/MPEG-4 AVC, as well asthe Society of Motion Picture & Television Engineers (SMPTE) 421M/VC-1,and Joint Photographic Experts Group (JPEG) formats such as JPEG, andMotion JPEG (MJPEG) formats.

In some embodiments, graphics processor 300 includes a block imagetransfer (BLIT) engine 304 to perform two-dimensional (2D) rasterizeroperations including, for example, bit-boundary block transfers.However, in one embodiment, 2D graphics operations are performed usingone or more components of graphics processing engine (GPE) 310. In someembodiments, graphics processing engine 310 is a compute engine forperforming graphics operations, including three-dimensional (3D)graphics operations and media operations.

In some embodiments, GPE 310 includes a 3D pipeline 312 for performing3D operations, such as rendering three-dimensional images and scenesusing processing functions that act upon 3D primitive shapes (e.g.,rectangle, triangle, etc.). The 3D pipeline 312 includes programmableand fixed function elements that perform various tasks within theelement and/or spawn execution threads to a 3D/Media sub-system 315.While 3D pipeline 312 can be used to perform media operations, anembodiment of GPE 310 also includes a media pipeline 316 that isspecifically used to perform media operations, such as videopost-processing and image enhancement.

In some embodiments, media pipeline 316 includes fixed function orprogrammable logic units to perform one or more specialized mediaoperations, such as video decode acceleration, video de-interlacing, andvideo encode acceleration in place of, or on behalf of video codecengine 306. In some embodiments, media pipeline 316 additionallyincludes a thread spawning unit to spawn threads for execution on3D/Media sub-system 315. The spawned threads perform computations forthe media operations on one or more graphics execution units included in3D/Media sub-system 315.

In some embodiments, 3D/Media subsystem 315 includes logic for executingthreads spawned by 3D pipeline 312 and media pipeline 316. In oneembodiment, the pipelines send thread execution requests to 3D/Mediasubsystem 315, which includes thread dispatch logic for arbitrating anddispatching the various requests to available thread executionresources. The execution resources include an array of graphicsexecution units to process the 3D and media threads. In someembodiments, 3D/Media subsystem 315 includes one or more internal cachesfor thread instructions and data. In some embodiments, the subsystemalso includes shared memory, including registers and addressable memory,to share data between threads and to store output data.

FIG. 9 is a block diagram of a graphics processing engine 410 of agraphics processor in accordance with some embodiments. In oneembodiment, the GPE 410 is a version of the GPE 310 shown in FIG. 8.Elements of FIG. 9 having the same reference numbers (or names) as theelements of any other figure herein can operate or function in anymanner similar to that described elsewhere herein, but are not limitedto such.

In some embodiments, GPE 410 couples with a command streamer 403, whichprovides a command stream to the GPE 3D and media pipelines 412, 416. Insome embodiments, command streamer 403 is coupled to memory, which canbe system memory, or one or more of internal cache memory and sharedcache memory. In some embodiments, command streamer 403 receivescommands from the memory and sends the commands to 3D pipeline 412and/or media pipeline 416. The commands are directives fetched from aring buffer, which stores commands for the 3D and media pipelines 412,416. In one embodiment, the ring buffer can additionally include batchcommand buffers storing batches of multiple commands. The 3D and mediapipelines 412, 416 process the commands by performing operations vialogic within the respective pipelines or by dispatching one or moreexecution threads to an execution unit array 414. In some embodiments,execution unit array 414 is scalable, such that the array includes avariable number of execution units based on the target power andperformance level of GPE 410.

In some embodiments, a sampling engine 430 couples with memory (e.g.,cache memory or system memory) and execution unit array 414. In someembodiments, sampling engine 430 provides a memory access mechanism forexecution unit array 414 that allows execution array 414 to readgraphics and media data from memory. In some embodiments, samplingengine 430 includes logic to perform specialized image samplingoperations for media.

In some embodiments, the specialized media sampling logic in samplingengine 430 includes a de-noise/de-interlace module 432, a motionestimation module 434, and an image scaling and filtering module 436. Insome embodiments, de-noise/de-interlace module 432 includes logic toperform one or more of a de-noise or a de-interlace algorithm on decodedvideo data. The de-interlace logic combines alternating fields ofinterlaced video content into a single fame of video. The de-noise logicreduces or removes data noise from video and image data. In someembodiments, the de-noise logic and de-interlace logic are motionadaptive and use spatial or temporal filtering based on the amount ofmotion detected in the video data. In some embodiments, thede-noise/de-interlace module 432 includes dedicated motion detectionlogic (e.g., within the motion estimation engine 434).

In some embodiments, motion estimation engine 434 provides hardwareacceleration for video operations by performing video accelerationfunctions such as motion vector estimation and prediction on video data.The motion estimation engine determines motion vectors that describe thetransformation of image data between successive video frames. In someembodiments, a graphics processor media codec uses video motionestimation engine 434 to perform operations on video at the macro-blocklevel that may otherwise be too computationally intensive to performwith a general-purpose processor. In some embodiments, motion estimationengine 434 is generally available to graphics processor components toassist with video decode and processing functions that are sensitive oradaptive to the direction or magnitude of the motion within video data.

In some embodiments, image scaling and filtering module 436 performsimage-processing operations to enhance the visual quality of generatedimages and video. In some embodiments, scaling and filtering module 436processes image and video data during the sampling operation beforeproviding the data to execution unit array 414.

In some embodiments, the GPE 410 includes a data port 444, whichprovides an additional mechanism for graphics subsystems to accessmemory. In some embodiments, data port 444 facilitates memory access foroperations including render target writes, constant buffer reads,scratch memory space reads/writes, and media surface accesses. In someembodiments, data port 444 includes cache memory space to cache accessesto memory. The cache memory can be a single data cache or separated intomultiple caches for the multiple subsystems that access memory via thedata port (e.g., a render buffer cache, a constant buffer cache, etc.).In some embodiments, threads executing on an execution unit in executionunit array 414 communicate with the data port by exchanging messages viaa data distribution interconnect that couples each of the sub-systems ofGPE 410.

FIG. 10 is a block diagram of another embodiment of a graphics processor500. Elements of FIG. 10 having the same reference numbers (or names) asthe elements of any other figure herein can operate or function in anymanner similar to that described elsewhere herein, but are not limitedto such.

In some embodiments, graphics processor 500 includes a ring interconnect502, a pipeline front-end 504, a media engine 537, and graphics cores580A-580N. In some embodiments, ring interconnect 502 couples thegraphics processor to other processing units, including other graphicsprocessors or one or more general-purpose processor cores. In someembodiments, the graphics processor is one of many processors integratedwithin a multi-core processing system.

In some embodiments, graphics processor 500 receives batches of commandsvia ring interconnect 502. The incoming commands are interpreted by acommand streamer 503 in the pipeline front-end 504. In some embodiments,graphics processor 500 includes scalable execution logic to perform 3Dgeometry processing and media processing via the graphics core(s)580A-580N. For 3D geometry processing commands, command streamer 503supplies commands to geometry pipeline 536. For at least some mediaprocessing commands, command streamer 503 supplies the commands to avideo front end 534, which couples with a media engine 537. In someembodiments, media engine 537 includes a Video Quality Engine (VQE) 530for video and image post-processing and a multi-format encode/decode(MFX) 533 engine to provide hardware-accelerated media data encode anddecode. In some embodiments, geometry pipeline 536 and media engine 537each generate execution threads for the thread execution resourcesprovided by at least one graphics core 580A.

In some embodiments, graphics processor 500 includes scalable threadexecution resources featuring modular cores 580A-580N (sometimesreferred to as core slices), each having multiple sub-cores 550A-550N,560A-560N (sometimes referred to as core sub-slices). In someembodiments, graphics processor 500 can have any number of graphicscores 580A through 580N. In some embodiments, graphics processor 500includes a graphics core 580A having at least a first sub-core 550A anda second core sub-core 560A. In other embodiments, the graphicsprocessor is a low power processor with a single sub-core (e.g., 550A).In some embodiments, graphics processor 500 includes multiple graphicscores 580A-580N, each including a set of first sub-cores 550A-550N and aset of second sub-cores 560A-560N. Each sub-core in the set of firstsub-cores 550A-550N includes at least a first set of execution units552A-552N and media/texture samplers 554A-554N. Each sub-core in the setof second sub-cores 560A-560N includes at least a second set ofexecution units 562A-562N and samplers 564A-564N. In some embodiments,each sub-core 550A-550N, 560A-560N shares a set of shared resources570A-570N. In some embodiments, the shared resources include sharedcache memory and pixel operation logic. Other shared resources may alsobe included in the various embodiments of the graphics processor.

FIG. 11 illustrates thread execution logic 600 including an array ofprocessing elements employed in some embodiments of a GPE. Elements ofFIG. 11 having the same reference numbers (or names) as the elements ofany other figure herein can operate or function in any manner similar tothat described elsewhere herein, but are not limited to such.

In some embodiments, thread execution logic 600 includes a pixel shader602, a thread dispatcher 604, instruction cache 606, a scalableexecution unit array including a plurality of execution units 608A-608N,a sampler 610, a data cache 612, and a data port 614. In one embodimentthe included components are interconnected via an interconnect fabricthat links to each of the components. In some embodiments, threadexecution logic 600 includes one or more connections to memory, such assystem memory or cache memory, through one or more of instruction cache606, data port 614, sampler 610, and execution unit array 608A-608N. Insome embodiments, each execution unit (e.g. 608A) is an individualvector processor capable of executing multiple simultaneous threads andprocessing multiple data elements in parallel for each thread. In someembodiments, execution unit array 608A-608N includes any numberindividual execution units.

In some embodiments, execution unit array 608A-608N is primarily used toexecute “shader” programs. In some embodiments, the execution units inarray 608A-608N execute an instruction set that includes native supportfor many standard 3D graphics shader instructions, such that shaderprograms from graphics libraries (e.g., Direct 3D and OpenGL) areexecuted with a minimal translation. The execution units support vertexand geometry processing (e.g., vertex programs, geometry programs,vertex shaders), pixel processing (e.g., pixel shaders, fragmentshaders) and general-purpose processing (e.g., compute and mediashaders).

Each execution unit in execution unit array 608A-608N operates on arraysof data elements. The number of data elements is the “execution size,”or the number of channels for the instruction. An execution channel is alogical unit of execution for data element access, masking, and flowcontrol within instructions. The number of channels may be independentof the number of physical Arithmetic Logic Units (ALUs) or FloatingPoint Units (FPUs) for a particular graphics processor. In someembodiments, execution units 608A-608N support integer andfloating-point data types.

The execution unit instruction set includes single instruction multipledata (SIMD) instructions. The various data elements can be stored as apacked data type in a register and the execution unit will process thevarious elements based on the data size of the elements. For example,when operating on a 256-bit wide vector, the 256 bits of the vector arestored in a register and the execution unit operates on the vector asfour separate 64-bit packed data elements (Quad-Word (QW) size dataelements), eight separate 32-bit packed data elements (Double Word (DW)size data elements), sixteen separate 16-bit packed data elements (Word(W) size data elements), or thirty-two separate 8-bit data elements(byte (B) size data elements). However, different vector widths andregister sizes are possible.

One or more internal instruction caches (e.g., 606) are included in thethread execution logic 600 to cache thread instructions for theexecution units. In some embodiments, one or more data caches (e.g.,612) are included to cache thread data during thread execution. In someembodiments, sampler 610 is included to provide texture sampling for 3Doperations and media sampling for media operations. In some embodiments,sampler 610 includes specialized texture or media sampling functionalityto process texture or media data during the sampling process beforeproviding the sampled data to an execution unit.

During execution, the graphics and media pipelines send threadinitiation requests to thread execution logic 600 via thread spawningand dispatch logic. In some embodiments, thread execution logic 600includes a local thread dispatcher 604 that arbitrates thread initiationrequests from the graphics and media pipelines and instantiates therequested threads on one or more execution units 608A-608N. For example,the geometry pipeline (e.g., 536 of FIG. 10) dispatches vertexprocessing, tessellation, or geometry processing threads to threadexecution logic 600 (FIG. 11). In some embodiments, thread dispatcher604 can also process runtime thread spawning requests from the executingshader programs.

Once a group of geometric objects has been processed and rasterized intopixel data, pixel shader 602 is invoked to further compute outputinformation and cause results to be written to output surfaces (e.g.,color buffers, depth buffers, stencil buffers, etc.). In someembodiments, pixel shader 602 calculates the values of the variousvertex attributes that are to be interpolated across the rasterizedobject. In some embodiments, pixel shader 602 then executes anapplication programming interface (API)-supplied pixel shader program.To execute the pixel shader program, pixel shader 602 dispatches threadsto an execution unit (e.g., 608A) via thread dispatcher 604. In someembodiments, pixel shader 602 uses texture sampling logic in sampler 610to access texture data in texture maps stored in memory. Arithmeticoperations on the texture data and the input geometry data compute pixelcolor data for each geometric fragment, or discards one or more pixelsfrom further processing.

In some embodiments, the data port 614 provides a memory accessmechanism for the thread execution logic 600 output processed data tomemory for processing on a graphics processor output pipeline. In someembodiments, the data port 614 includes or couples to one or more cachememories (e.g., data cache 612) to cache data for memory access via thedata port.

FIG. 12 is a block diagram illustrating a graphics processor instructionformats 700 according to some embodiments. In one or more embodiment,the graphics processor execution units support an instruction set havinginstructions in multiple formats. The solid lined boxes illustrate thecomponents that are generally included in an execution unit instruction,while the dashed lines include components that are optional or that areonly included in a sub-set of the instructions. In some embodiments,instruction format 700 described and illustrated are macro-instructions,in that they are instructions supplied to the execution unit, as opposedto micro-operations resulting from instruction decode once theinstruction is processed.

In some embodiments, the graphics processor execution units nativelysupport instructions in a 128-bit format 710. A 64-bit compactedinstruction format 730 is available for some instructions based on theselected instruction, instruction options, and number of operands. Thenative 128-bit format 710 provides access to all instruction options,while some options and operations are restricted in the 64-bit format730. The native instructions available in the 64-bit format 730 vary byembodiment. In some embodiments, the instruction is compacted in partusing a set of index values in an index field 713. The execution unithardware references a set of compaction tables based on the index valuesand uses the compaction table outputs to reconstruct a nativeinstruction in the 128-bit format 710.

For each format, instruction opcode 712 defines the operation that theexecution unit is to perform. The execution units execute eachinstruction in parallel across the multiple data elements of eachoperand. For example, in response to an add instruction the executionunit performs a simultaneous add operation across each color channelrepresenting a texture element or picture element. By default, theexecution unit performs each instruction across all data channels of theoperands. In some embodiments, instruction control field 714 enablescontrol over certain execution options, such as channels selection(e.g., predication) and data channel order (e.g., swizzle). For 128-bitinstructions 710 an exec-size field 716 limits the number of datachannels that will be executed in parallel. In some embodiments,exec-size field 716 is not available for use in the 64-bit compactinstruction format 730.

Some execution unit instructions have up to three operands including twosource operands, src0 722, src1 722, and one destination 718. In someembodiments, the execution units support dual destination instructions,where one of the destinations is implied. Data manipulation instructionscan have a third source operand (e.g., SRC2 724), where the instructionopcode 712 determines the number of source operands. An instruction'slast source operand can be an immediate (e.g., hard-coded) value passedwith the instruction.

In some embodiments, the 128-bit instruction format 710 includes anaccess/address mode information 726 specifying, for example, whetherdirect register addressing mode or indirect register addressing mode isused. When direct register addressing mode is used, the register addressof one or more operands is directly provided by bits in the instruction710.

In some embodiments, the 128-bit instruction format 710 includes anaccess/address mode field 726, which specifies an address mode and/or anaccess mode for the instruction. In one embodiment the access mode todefine a data access alignment for the instruction. Some embodimentssupport access modes including a 16-byte aligned access mode and a1-byte aligned access mode, where the byte alignment of the access modedetermines the access alignment of the instruction operands. Forexample, when in a first mode, the instruction 710 may use byte-alignedaddressing for source and destination operands and when in a secondmode, the instruction 710 may use 16-byte-aligned addressing for allsource and destination operands.

In one embodiment, the address mode portion of the access/address modefield 726 determines whether the instruction is to use direct orindirect addressing. When direct register addressing mode is used bitsin the instruction 710 directly provide the register address of one ormore operands. When indirect register addressing mode is used, theregister address of one or more operands may be computed based on anaddress register value and an address immediate field in theinstruction.

In some embodiments instructions are grouped based on opcode 712bit-fields to simplify Opcode decode 740. For an 8-bit opcode, bits 4,5, and 6 allow the execution unit to determine the type of opcode. Theprecise opcode grouping shown is merely an example. In some embodiments,a move and logic opcode group 742 includes data movement and logicinstructions (e.g., move (mov), compare (cmp)). In some embodiments,move and logic group 742 shares the five most significant bits (MSB),where move (mov) instructions are in the form of 0000xxxxb and logicinstructions are in the form of 0001xxxxb. A flow control instructiongroup 744 (e.g., call, jump (jmp)) includes instructions in the form of0010xxxxb (e.g., 0×20). A miscellaneous instruction group 746 includes amix of instructions, including synchronization instructions (e.g., wait,send) in the form of 0011xxxxb (e.g., 0×30). A parallel math instructiongroup 748 includes component-wise arithmetic instructions (e.g., add,multiply (mul)) in the form of 0100xxxxb (e.g., 0×40). The parallel mathgroup 748 performs the arithmetic operations in parallel across datachannels. The vector math group 750 includes arithmetic instructions(e.g., dp4) in the form of 0101xxxxb (e.g., 0×50). The vector math groupperforms arithmetic such as dot product calculations on vector operands.

FIG. 13 is a block diagram of another embodiment of a graphics processor800. Elements of FIG. 13 having the same reference numbers (or names) asthe elements of any other figure herein can operate or function in anymanner similar to that described elsewhere herein, but are not limitedto such.

In some embodiments, graphics processor 800 includes a graphics pipeline820, a media pipeline 830, a display engine 840, thread execution logic850, and a render output pipeline 870. In some embodiments, graphicsprocessor 800 is a graphics processor within a multi-core processingsystem that includes one or more general purpose processing cores. Thegraphics processor is controlled by register writes to one or morecontrol registers (not shown) or via commands issued to graphicsprocessor 800 via a ring interconnect 802. In some embodiments, ringinterconnect 802 couples graphics processor 800 to other processingcomponents, such as other graphics processors or general-purposeprocessors. Commands from ring interconnect 802 are interpreted by acommand streamer 803, which supplies instructions to individualcomponents of graphics pipeline 820 or media pipeline 830.

In some embodiments, command streamer 803 directs the operation of avertex fetcher 805 that reads vertex data from memory and executesvertex-processing commands provided by command streamer 803. In someembodiments, vertex fetcher 805 provides vertex data to a vertex shader807, which performs coordinate space transformation and lightingoperations to each vertex. In some embodiments, vertex fetcher 805 andvertex shader 807 execute vertex-processing instructions by dispatchingexecution threads to execution units 852A, 852B via a thread dispatcher831.

In some embodiments, execution units 852A, 852B are an array of vectorprocessors having an instruction set for performing graphics and mediaoperations. In some embodiments, execution units 852A, 852B have anattached L1 cache 851 that is specific for each array or shared betweenthe arrays. The cache can be configured as a data cache, an instructioncache, or a single cache that is partitioned to contain data andinstructions in different partitions.

In some embodiments, graphics pipeline 820 includes tessellationcomponents to perform hardware-accelerated tessellation of 3D objects.In some embodiments, a programmable hull shader 811 configures thetessellation operations. A programmable domain shader 817 providesback-end evaluation of tessellation output. A tessellator 813 operatesat the direction of hull shader 811 and contains special purpose logicto generate a set of detailed geometric objects based on a coarsegeometric model that is provided as input to graphics pipeline 820. Insome embodiments, if tessellation is not used, tessellation components811, 813, 817 can be bypassed.

In some embodiments, complete geometric objects can be processed by ageometry shader 819 via one or more threads dispatched to executionunits 852A, 852B, or can proceed directly to the clipper 829. In someembodiments, the geometry shader operates on entire geometric objects,rather than vertices or patches of vertices as in previous stages of thegraphics pipeline. If the tessellation is disabled the geometry shader819 receives input from the vertex shader 807. In some embodiments,geometry shader 819 is programmable by a geometry shader program toperform geometry tessellation if the tessellation units are disabled.

Before rasterization, a clipper 829 processes vertex data. The clipper829 may be a fixed function clipper or a programmable clipper havingclipping and geometry shader functions. In some embodiments, arasterizer/depth 873 in the render output pipeline 870 dispatches pixelshaders to convert the geometric objects into their per pixelrepresentations. In some embodiments, pixel shader logic is included inthread execution logic 850. In some embodiments, an application canbypass the rasterizer 873 and access un-rasterized vertex data via astream out unit 823.

The graphics processor 800 has an interconnect bus, interconnect fabric,or some other interconnect mechanism that allows data and messagepassing amongst the major components of the processor. In someembodiments, execution units 852A, 852B and associated cache(s) 851,texture and media sampler 854, and texture/sampler cache 858interconnect via a data port 856 to perform memory access andcommunicate with render output pipeline components of the processor. Insome embodiments, sampler 854, caches 851, 858 and execution units 852A,852B each have separate memory access paths.

In some embodiments, render output pipeline 870 contains a rasterizerand depth test component 873 that converts vertex-based objects into anassociated pixel-based representation. In some embodiments, therasterizer logic includes a windower/masker unit to perform fixedfunction triangle and line rasterization. An associated render cache 878and depth cache 879 are also available in some embodiments. A pixeloperations component 877 performs pixel-based operations on the data,though in some instances, pixel operations associated with 2D operations(e.g. bit block image transfers with blending) are performed by the 2Dengine 841, or substituted at display time by the display controller 843using overlay display planes. In some embodiments, a shared L3 cache 875is available to all graphics components, allowing the sharing of datawithout the use of main system memory.

In some embodiments, graphics processor media pipeline 830 includes amedia engine 837 and a video front end 834. In some embodiments, videofront end 834 receives pipeline commands from the command streamer 803.In some embodiments, media pipeline 830 includes a separate commandstreamer. In some embodiments, video front-end 834 processes mediacommands before sending the command to the media engine 837. In someembodiments, media engine 337 includes thread spawning functionality tospawn threads for dispatch to thread execution logic 850 via threaddispatcher 831.

In some embodiments, graphics processor 800 includes a display engine840. In some embodiments, display engine 840 is external to processor800 and couples with the graphics processor via the ring interconnect802, or some other interconnect bus or fabric. In some embodiments,display engine 840 includes a 2D engine 841 and a display controller843. In some embodiments, display engine 840 contains special purposelogic capable of operating independently of the 3D pipeline. In someembodiments, display controller 843 couples with a display device (notshown), which may be a system integrated display device, as in a laptopcomputer, or an external display device attached via a display deviceconnector.

In some embodiments, graphics pipeline 820 and media pipeline 830 areconfigurable to perform operations based on multiple graphics and mediaprogramming interfaces and are not specific to any one applicationprogramming interface (API). In some embodiments, driver software forthe graphics processor translates API calls that are specific to aparticular graphics or media library into commands that can be processedby the graphics processor. In some embodiments, support is provided forthe Open Graphics Library (OpenGL) and Open Computing Language (OpenCL)from the Khronos Group, the Direct3D library from the MicrosoftCorporation, or support may be provided to both OpenGL and D3D. Supportmay also be provided for the Open Source Computer Vision Library(OpenCV). A future API with a compatible 3D pipeline would also besupported if a mapping can be made from the pipeline of the future APIto the pipeline of the graphics processor.

FIG. 14A is a block diagram illustrating a graphics processor commandformat 900 according to some embodiments. FIG. 14B is a block diagramillustrating a graphics processor command sequence 910 according to anembodiment. The solid lined boxes in FIG. 14A illustrate the componentsthat are generally included in a graphics command while the dashed linesinclude components that are optional or that are only included in asub-set of the graphics commands. The exemplary graphics processorcommand format 900 of FIG. 14A includes data fields to identify a targetclient 902 of the command, a command operation code (opcode) 904, andthe relevant data 906 for the command. A sub-opcode 905 and a commandsize 908 are also included in some commands.

In some embodiments, client 902 specifies the client unit of thegraphics device that processes the command data. In some embodiments, agraphics processor command parser examines the client field of eachcommand to condition the further processing of the command and route thecommand data to the appropriate client unit. In some embodiments, thegraphics processor client units include a memory interface unit, arender unit, a 2D unit, a 3D unit, and a media unit. Each client unithas a corresponding processing pipeline that processes the commands.Once the command is received by the client unit, the client unit readsthe opcode 904 and, if present, sub-opcode 905 to determine theoperation to perform. The client unit performs the command usinginformation in data field 906. For some commands an explicit commandsize 908 is expected to specify the size of the command. In someembodiments, the command parser automatically determines the size of atleast some of the commands based on the command opcode. In someembodiments commands are aligned via multiples of a double word.

The flow diagram in FIG. 14B shows an exemplary graphics processorcommand sequence 910. In some embodiments, software or firmware of adata processing system that features an embodiment of a graphicsprocessor uses a version of the command sequence shown to set up,execute, and terminate a set of graphics operations. A sample commandsequence is shown and described for purposes of example only asembodiments are not limited to these specific commands or to thiscommand sequence. Moreover, the commands may be issued as batch ofcommands in a command sequence, such that the graphics processor willprocess the sequence of commands in at least partially concurrence.

In some embodiments, the graphics processor command sequence 910 maybegin with a pipeline flush command 912 to cause any active graphicspipeline to complete the currently pending commands for the pipeline. Insome embodiments, the 3D pipeline 922 and the media pipeline 924 do notoperate concurrently. The pipeline flush is performed to cause theactive graphics pipeline to complete any pending commands. In responseto a pipeline flush, the command parser for the graphics processor willpause command processing until the active drawing engines completepending operations and the relevant read caches are invalidated.Optionally, any data in the render cache that is marked ‘dirty’ can beflushed to memory. In some embodiments, pipeline flush command 912 canbe used for pipeline synchronization or before placing the graphicsprocessor into a low power state.

In some embodiments, a pipeline select command 913 is used when acommand sequence requires the graphics processor to explicitly switchbetween pipelines. In some embodiments, a pipeline select command 913 isrequired only once within an execution context before issuing pipelinecommands unless the context is to issue commands for both pipelines. Insome embodiments, a pipeline flush command is 912 is requiredimmediately before a pipeline switch via the pipeline select command913.

In some embodiments, a pipeline control command 914 configures agraphics pipeline for operation and is used to program the 3D pipeline922 and the media pipeline 924. In some embodiments, pipeline controlcommand 914 configures the pipeline state for the active pipeline. Inone embodiment, the pipeline control command 914 is used for pipelinesynchronization and to clear data from one or more cache memories withinthe active pipeline before processing a batch of commands.

In some embodiments, return buffer state commands 916 are used toconfigure a set of return buffers for the respective pipelines to writedata. Some pipeline operations require the allocation, selection, orconfiguration of one or more return buffers into which the operationswrite intermediate data during processing. In some embodiments, thegraphics processor also uses one or more return buffers to store outputdata and to perform cross thread communication. In some embodiments, thereturn buffer state 916 includes selecting the size and number of returnbuffers to use for a set of pipeline operations.

The remaining commands in the command sequence differ based on theactive pipeline for operations. Based on a pipeline determination 920,the command sequence is tailored to the 3D pipeline 922 beginning withthe 3D pipeline state 930, or the media pipeline 924 beginning at themedia pipeline state 940.

The commands for the 3D pipeline state 930 include 3D state settingcommands for vertex buffer state, vertex element state, constant colorstate, depth buffer state, and other state variables that are to beconfigured before 3D primitive commands are processed. The values ofthese commands are determined at least in part based the particular 3DAPI in use. In some embodiments, 3D pipeline state 930 commands are alsoable to selectively disable or bypass certain pipeline elements if thoseelements will not be used.

In some embodiments, 3D primitive 932 command is used to submit 3Dprimitives to be processed by the 3D pipeline. Commands and associatedparameters that are passed to the graphics processor via the 3Dprimitive 932 command are forwarded to the vertex fetch function in thegraphics pipeline. The vertex fetch function uses the 3D primitive 932command data to generate vertex data structures. The vertex datastructures are stored in one or more return buffers. In someembodiments, 3D primitive 932 command is used to perform vertexoperations on 3D primitives via vertex shaders. To process vertexshaders, 3D pipeline 922 dispatches shader execution threads to graphicsprocessor execution units.

In some embodiments, 3D pipeline 922 is triggered via an execute 934command or event. In some embodiments, a register write triggers commandexecution. In some embodiments execution is triggered via a ‘go’ or‘kick’ command in the command sequence. In one embodiment commandexecution is triggered using a pipeline synchronization command to flushthe command sequence through the graphics pipeline. The 3D pipeline willperform geometry processing for the 3D primitives. Once operations arecomplete, the resulting geometric objects are rasterized and the pixelengine colors the resulting pixels. Additional commands to control pixelshading and pixel back end operations may also be included for thoseoperations.

In some embodiments, the graphics processor command sequence 910 followsthe media pipeline 924 path when performing media operations. Ingeneral, the specific use and manner of programming for the mediapipeline 924 depends on the media or compute operations to be performed.Specific media decode operations may be offloaded to the media pipelineduring media decode. In some embodiments, the media pipeline can also bebypassed and media decode can be performed in whole or in part usingresources provided by one or more general purpose processing cores. Inone embodiment, the media pipeline also includes elements forgeneral-purpose graphics processor unit (GPGPU) operations, where thegraphics processor is used to perform SIMD vector operations usingcomputational shader programs that are not explicitly related to therendering of graphics primitives.

In some embodiments, media pipeline 924 is configured in a similarmanner as the 3D pipeline 922. A set of media pipeline state commands940 are dispatched or placed into in a command queue before the mediaobject commands 942. In some embodiments, media pipeline state commands940 include data to configure the media pipeline elements that will beused to process the media objects. This includes data to configure thevideo decode and video encode logic within the media pipeline, such asencode or decode format. In some embodiments, media pipeline statecommands 940 also support the use one or more pointers to “indirect”state elements that contain a batch of state settings.

In some embodiments, media object commands 942 supply pointers to mediaobjects for processing by the media pipeline. The media objects includememory buffers containing video data to be processed. In someembodiments, all media pipeline states must be valid before issuing amedia object command 942. Once the pipeline state is configured andmedia object commands 942 are queued, the media pipeline 924 istriggered via an execute command 944 or an equivalent execute event(e.g., register write). Output from media pipeline 924 may then be postprocessed by operations provided by the 3D pipeline 922 or the mediapipeline 924. In some embodiments, GPGPU operations are configured andexecuted in a similar manner as media operations.

FIG. 15 illustrates exemplary graphics software architecture for a dataprocessing system 1000 according to some embodiments. In someembodiments, software architecture includes a 3D graphics application1010, an operating system 1020, and at least one processor 1030. In someembodiments, processor 1030 includes a graphics processor 1032 and oneor more general-purpose processor core(s) 1034. The graphics application1010 and operating system 1020 each execute in the system memory 1050 ofthe data processing system.

In some embodiments, 3D graphics application 1010 contains one or moreshader programs including shader instructions 1012. The shader languageinstructions may be in a high-level shader language, such as the HighLevel Shader Language (HLSL) or the OpenGL Shader Language (GLSL). Theapplication also includes executable instructions 1014 in a machinelanguage suitable for execution by the general-purpose processor core1034. The application also includes graphics objects 1016 defined byvertex data.

In some embodiments, operating system 1020 is a Microsoft® Windows®operating system from the Microsoft Corporation, a proprietary UNIX-likeoperating system, or an open source UNIX-like operating system using avariant of the Linux kernel. When the Direct3D API is in use, theoperating system 1020 uses a front-end shader compiler 1024 to compileany shader instructions 1012 in HLSL into a lower-level shader language.The compilation may be a just-in-time (JIT) compilation or theapplication can perform shader pre-compilation. In some embodiments,high-level shaders are compiled into low-level shaders during thecompilation of the 3D graphics application 1010.

In some embodiments, user mode graphics driver 1026 contains a back-endshader compiler 1027 to convert the shader instructions 1012 into ahardware specific representation. When the OpenGL API is in use, shaderinstructions 1012 in the GLSL high-level language are passed to a usermode graphics driver 1026 for compilation. In some embodiments, usermode graphics driver 1026 uses operating system kernel mode functions1028 to communicate with a kernel mode graphics driver 1029. In someembodiments, kernel mode graphics driver 1029 communicates with graphicsprocessor 1032 to dispatch commands and instructions.

One or more aspects of at least one embodiment may be implemented byrepresentative code stored on a machine-readable medium which representsand/or defines logic within an integrated circuit such as a processor.For example, the machine-readable medium may include instructions whichrepresent various logic within the processor. When read by a machine,the instructions may cause the machine to fabricate the logic to performthe techniques described herein. Such representations, known as “IPcores,” are reusable units of logic for an integrated circuit that maybe stored on a tangible, machine-readable medium as a hardware modelthat describes the structure of the integrated circuit. The hardwaremodel may be supplied to various customers or manufacturing facilities,which load the hardware model on fabrication machines that manufacturethe integrated circuit. The integrated circuit may be fabricated suchthat the circuit performs operations described in association with anyof the embodiments described herein.

FIG. 16 is a block diagram illustrating an IP core development system1100 that may be used to manufacture an integrated circuit to performoperations according to an embodiment. The IP core development system1100 may be used to generate modular, re-usable designs that can beincorporated into a larger design or used to construct an entireintegrated circuit (e.g., an SOC integrated circuit). A design facility1130 can generate a software simulation 1110 of an IP core design in ahigh level programming language (e.g., C/C++). The software simulation1110 can be used to design, test, and verify the behavior of the IPcore. A register transfer level (RTL) design can then be created orsynthesized from the simulation model 1100. The RTL design 1115 is anabstraction of the behavior of the integrated circuit that models theflow of digital signals between hardware registers, including theassociated logic performed using the modeled digital signals. Inaddition to an RTL design 1115, lower-level designs at the logic levelor transistor level may also be created, designed, or synthesized. Thus,the particular details of the initial design and simulation may vary.

The RTL design 1115 or equivalent may be further synthesized by thedesign facility into a hardware model 1120, which may be in a hardwaredescription language (HDL), or some other representation of physicaldesign data. The HDL may be further simulated or tested to verify the IPcore design. The IP core design can be stored for delivery to a 3 ^(rd)party fabrication facility 1165 using non-volatile memory 1140 (e.g.,hard disk, flash memory, or any non-volatile storage medium).Alternatively, the IP core design may be transmitted (e.g., via theInternet) over a wired connection 1150 or wireless connection 1160. Thefabrication facility 1165 may then fabricate an integrated circuit thatis based at least in part on the IP core design. The fabricatedintegrated circuit can be configured to perform operations in accordancewith at least one embodiment described herein.

FIG. 17 is a block diagram illustrating an exemplary system on a chipintegrated circuit 1200 that may be fabricated using one or more IPcores, according to an embodiment. The exemplary integrated circuitincludes one or more application processors 1205 (e.g., CPUs), at leastone graphics processor 1210, and may additionally include an imageprocessor 1215 and/or a video processor 1220, any of which may be amodular IP core from the same or multiple different design facilities.The integrated circuit includes peripheral or bus logic including a USBcontroller 1225, UART controller 1230, an SPI/SDIO controller 1235, andan I²S/I²C controller 1240. Additionally, the integrated circuit caninclude a display device 1245 coupled to one or more of ahigh-definition multimedia interface (HDMI) controller 1250 and a mobileindustry processor interface (MIPI) display interface 1255. Storage maybe provided by a flash memory subsystem 1260 including flash memory anda flash memory controller. Memory interface may be provided via a memorycontroller 1265 for access to SDRAM or SRAM memory devices. Someintegrated circuits additionally include an embedded security engine1270.

Additionally, other logic and circuits may be included in the processorof integrated circuit 1200, including additional graphicsprocessors/cores, peripheral interface controllers, or general purposeprocessor cores.

The following clauses and/or examples pertain to further embodiments:

One example embodiment may be a method comprising compressing colorvalues using a palette based encoder, finding clusters of color valuesand encoding color values within the cluster with respect to a colorvalue having a predefined characteristic, and encoding clusters thathave pixels or samples with constant color value. The method may alsoinclude wherein said pre-defined characteristic is the sample or pixelwith the minimum color value within the cluster. The method may alsoinclude encoding the fact that a color channel is constant. The methodmay also include encoding residuals relative to the sample or pixel withthe predefined characteristic of the cluster that minimizes cost. Themethod may also include refraining from encoding residuals for a clusterwith a constant color. The method may also include using a bit for eachchannel to encode whether it is constant color or not. The method mayalso include providing a group of bits per color channel to indicate howmany residual bits are needed per channel. The method may also includewherein finding clusters includes using a K-means clustering algorithm.The method may also include finding a minimal bounding box around acolor. The method may also include taking a first color from a palette,building a cluster around the first color and then, if a second colorthat is different by a threshold from the first color, forming a secondcluster including the second color, and fitting ensuring colors into thefirst and second clusters.

In another example embodiment may be one or more non-transitory computerreadable media storing instructions executed by a processor to perform asequence comprising compressing color values using a palette basedencoder, finding clusters of color values and encoding color valueswithin the cluster with respect to a color value having a predefinedcharacteristic, and encoding clusters that have pixels or samples withconstant color value. The media may further store instructions whereinsaid pre-defined characteristic is the sample or pixel with the minimumcolor value within the cluster. The media may further store instructionsto perform a sequence including encoding the fact that a color channelis constant. The media may further store instructions to perform asequence including encoding residuals relative to the sample or pixelwith the predefined characteristic of the cluster that minimizes cost.The media may further store instructions to perform a sequence includingrefraining from encoding residuals for a cluster with a constant color.The media may further store instructions to perform a sequence includingusing a bit for each channel to encode whether it is constant color ornot. The media may further store instructions to perform a sequenceincluding providing a group of bits per color channel to indicate howmany residual bits are needed per channel. The media may further storeinstructions wherein finding clusters includes using a K-meansclustering algorithm. The media may further store instructions toperform a sequence including finding a minimal bounding box around acolor. The media may further store instructions to perform a sequenceincluding taking a first color from a palette, building a cluster aroundthe first color and then, if a second color that is different by athreshold from the first color, forming a second cluster including thesecond color, and fitting ensuring colors into the first and secondclusters.

Another example embodiment may be an apparatus comprising a processor tocompress color values using a palette based encoder, find clusters ofcolor values and encoding color values within the cluster with respectto a color value having a predefined characteristic, and encode clustersthat have pixels or samples with constant color value, and a storagecoupled to said processor. The apparatus may include wherein saidpre-defined characteristic is the sample or pixel with the minimum colorvalue within the cluster. The apparatus may include said processor toencode the fact that a color channel is constant. The apparatus mayinclude said processor to encode residuals relative to the sample orpixel with the predefined characteristic of the cluster that minimizescost. The apparatus may include said processor to refrain from encodingresiduals for a cluster with a constant color. The apparatus may includesaid processor to use a bit for each channel to encode whether it isconstant color or not. The apparatus may include said processor toprovide a group of bits per color channel to indicate how many residualbits are needed per channel. The apparatus may include said processor tofind clusters using a K-means clustering algorithm. The apparatus mayinclude said processor to find a minimal bounding box around a color.The apparatus may include said processor to take a first color from apalette, build a cluster around the first color and then, if a secondcolor that is different by a threshold from the first color, form asecond cluster including the second color, and fit ensuring colors intothe first and second clusters.

The graphics processing techniques described herein may be implementedin various hardware architectures. For example, graphics functionalitymay be integrated within a chipset. Alternatively, a discrete graphicsprocessor may be used. As still another embodiment, the graphicsfunctions may be implemented by a general purpose processor, including amulticore processor.

References throughout this specification to “one embodiment” or “anembodiment” mean that a particular feature, structure, or characteristicdescribed in connection with the embodiment is included in at least oneimplementation encompassed within the present disclosure. Thus,appearances of the phrase “one embodiment” or “in an embodiment” are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be instituted inother suitable forms other than the particular embodiment illustratedand all such forms may be encompassed within the claims of the presentapplication.

While a limited number of embodiments have been described, those skilledin the art will appreciate numerous modifications and variationstherefrom. It is intended that the appended claims cover all suchmodifications and variations as fall within the true spirit and scope ofthis disclosure.

1. A method comprising: compressing color values using a palette basedencoder; finding clusters of color values and encoding color valueswithin the cluster with respect to a color value having a predefinedcharacteristic; and encoding clusters that have pixels or samples withconstant color value.
 2. The method of claim 1 wherein said pre-definedcharacteristic is the sample or pixel with the minimum color valuewithin the cluster.
 3. The method of claim 1 including encoding the factthat a color channel is constant.
 4. The method of claim 1 includingencoding residuals relative to a sample or pixel with the predefinedcharacteristic of the cluster that minimizes cost, where residualsencode a difference between a color of a sample or pixel with respect tothe color value having the predefined characteristics.
 5. The method ofclaim 4 including refraining from encoding residuals for a cluster witha constant color.
 6. The method of claim 3 including using a bit foreach channel to encode information about whether it is constant color.7. The method of claim 4 including providing a group of bits per colorchannel to indicate how many residual bits are needed per channel. 8.The method of claim 1 wherein finding clusters includes using a K-meansclustering algorithm.
 9. The method of claim 8 including finding aminimal bounding box around a color.
 10. The method of claim 1 includingtaking a first color from a palette, building a cluster around the firstcolor and then, if a second color that is different by a threshold fromthe first color, forming a second cluster including the second color,and fitting ensuing colors into the first and second clusters.
 11. Oneor more non-transitory computer readable media storing instructionsexecuted by a processor to perform a sequence comprising: compressingcolor values using a palette based encoder; finding clusters of colorvalues and encoding color values within the cluster with respect to acolor value having a predefined characteristic; and encoding clustersthat have pixels or samples with constant color value.
 12. The media ofclaim 11 wherein said pre-defined characteristic is the sample or pixelwith the minimum color value within the cluster.
 13. The media of claim11, said sequence including encoding the fact that a color channel isconstant.
 14. The media of claim 11, said sequence including encodingresiduals relative to a sample or pixel with the predefinedcharacteristic of the cluster that minimizes cost, where residualsencode a difference between a color of a sample or pixel with respect tothe color value having the predefined characteristics.
 15. The media ofclaim 14, said sequence including refraining from encoding residuals fora cluster with a constant color.
 16. The media of claim 13, saidsequence including using a bit for each channel to encode informationabout whether it is constant color.
 17. The media of claim 14, saidsequence including providing a group of bits per color channel toindicate how many residual bits are needed per channel.
 18. The media ofclaim 11 wherein finding clusters includes using a K-means clusteringalgorithm.
 19. The media of claim 18, said sequence including finding aminimal bounding box around a color.
 20. The media of claim 11, saidsequence including taking a first color from a palette, building acluster around the first color and then, if a second color that isdifferent by a threshold from the first color, forming a second clusterincluding the second color, and fitting ensuing colors into the firstand second clusters.
 21. An apparatus comprising: a processor tocompress color values using a palette based encoder, find clusters ofcolor values and encoding color values within the cluster with respectto a color value having a predefined characteristic, and encode clustersthat have pixels or samples with constant color value; and a storagecoupled to said processor.
 22. The apparatus of claim 21 wherein saidpre-defined characteristic is the sample or pixel with the minimum colorvalue within the cluster.
 23. The apparatus of claim 21, said processorto encode that a color channel is constant.
 24. The apparatus of claim21, said processor to encode residuals relative to a sample or pixelwith the predefined characteristic of the cluster that minimizes cost,where residuals encode a difference between a color of a sample or pixelwith respect to the color value having the predefined characteristics.25. The apparatus of claim 24, said processor to refrain from encodingresiduals for a cluster with a constant color.
 26. The apparatus ofclaim 23, said processor to use a bit for each channel to encodeinformation about whether it is constant color.
 27. The apparatus ofclaim 24, said processor to provide a group of bits per color channel toindicate how many residual bits are needed per channel.
 28. Theapparatus of claim 21, said processor to find clusters using a K-meansclustering algorithm.
 29. The apparatus of claim 28, said processor tofind a minimal bounding box around a color.
 30. The apparatus of claim21, said processor to take a first color from a palette, build a clusteraround the first color and then, if a second color that is different bya threshold from the first color, form a second cluster including thesecond color, and fit ensuing colors into the first and second clusters.